The present invention relates generally to analyzers that measure the carbon content of a sample. More specifically, the invention relates to chemical analyzers that can measure the total organic carbon ("TOC"), the inorganic carbon ("IC"), or the total carbon ("TC"; TC=TOC+IC) content of a sample or specimen.
The measurement of carbon content in liquids such as drinking water, treated or untreated wastewater, and ultrapure water for pharmaceutical or clean room applications is a routine way to assess the purity of the liquid sample. Solid or semi-solid specimens such as soils, clays, or sediments can likewise be measured for carbon content using known analyzer accessories.
Syringe pumps have been used in prior art dissolved carbon analyzers, but generally only in those that use a combustion-type reactor to convert dissolved organic carbon to gaseous CO.sub.2. Such combustion reactors can accept only relatively small volumes (less than about 2.5 ml) of the sample of interest; therefore, the syringe pumps used in the prior art have had low volume (2.5 ml) capacities. Prior art analyzers that use the known UV or UV/persulfate or heated/persulfate techniques have generally used a peristaltic pump in series with a fixed volume sample loop to dispense the sample of interest. Ultraviolet ("UV") reaction chambers can accept larger volumes (up to about 25 ml) of the sample of interest, permitting measurement of lower concentrations of dissolved carbon in the sample. An object of the invention is to combine the flexibility of a syringe pump for dispensing sample with the high sensitivity UV reaction technique.
Prior art dissolved carbon analyzers, particularly those utilizing the known UV, UV/persulfate, or heated/persulfate oxidation techniques, have used a multiplicity of valves, connections, and tubing connected together in a complicated arrangement that increases the likelihood of leaks or contamination and makes diagnosis of instrument problems very difficult. Therefore another object of the invention is to simplify the flow path of a dissolved carbon analyzer by incorporation of a syringe pump and multiple-port valve.
Known dissolved carbon analyzers use flexible tubes to carry fluids between valves, connections, and other components of the analyzer. When servicing such analyzers, it becomes very difficult to identify and track any particular tube or series of tubes because the tubes are grouped together at various locations and all have the same appearance. Thus another object of the invention is to facilitate the identification or tracking of tubes in a dissolved carbon analyzer.
Other objects of the invention will become apparent from the detailed description of the invention and the accompanying drawings.